This invention relates to a method of and apparatus for periodically cleaning stationary filter boxes each containing a first air flow generating unit and a filter disposed upstream thereof. The air to be cleaned which carries solid impurities is drawn through the filter by the first air flow generating unit.
In particular, but in no way exclusively, the invention is concerned with the cleaning of filter boxes used in the textile industry with air suction (vacuum) systems associated with textile machines such as knitting, spinning, or weaving machines, Jacquard looms or the like.
In vacuum systems of the aforenoted type the drawn air contains solid impurities such as fibers, dust specks, yarn fragments or the like, which have to be separated from the air stream. The cleaning of the air is effected in filter boxes in which the air traverses one or more filters. For purposes of substantial economy and automation it is desirable to effect the cleaning and the emptying of the filter boxes automatically. There are known various measures for continuously cleaning a filter of a filter box to avoid the necessity of interrupting the drawing of the impure air during the cleaning of the filter.
These known filter boxes, however, are of expensive structure and have the particular disadvantage that the impurities stopped by the filter are not removed automatically from the filter box; this operation has to be performed manually as before.
There are further known filter boxes in which the filter is not cleaned continuously. Although such filter boxes may have a simple structure, they have the disadvantage that for the cleaning of the filter and for emptying the filter box the air suction (that is, the cleaning of air by the filter) has to be interrupted. For avoiding this disadvantage, there are known filter boxes which have two separate air flow chambers with built-in filters for the air to be cleaned. At any time air is guided only through one of the two flow chambers, while the other, temporarily idle chamber, is submitted to a manual cleaning and emptying operation. Although in filter boxes of this type the suction of the air to be cleaned does not have to be interrupted, the cleaning and emptying of the filter box still has to be performed manually.